<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        div span{
            color:red;

        }
        div>span{
            background-color: orange;
        }
    </style>
</head>
<body>
    <div>
        <span>div->span</span>
        <b>加粗</b>
        <p>
            <span>div->p->span</span>
        </p>
        <b>加粗</b>
    </div>
</body>
</html>